There are three types of ampules that are presently known: a pressurized ampule, an evacuated ampule and a non-pressurized ampule. The pressurized ampule contains fluid or powder which is at a pressure greater than atmospheric pressure such that the fluid or powder is propelled from the ampule by breaking the tip of the ampule. This type of ampule is manufactured by introducing the fluid or powder into the opened tip end of the ampule in a pressurized atmosphere and thereafter sealing the ampule.
The evacuated ampule is primarily designed for conducting chemical analyses of water. The evacuated ampule contains a fluid at a pressure that is less than atmospheric pressure. The analysis is conducted by breaking the tip of the ampule while immersed in the water being analyzed. Due to the low pressure in the ampule relative to the environment, the water is forced into the ampule and mixes with the analyzing fluid or powder. The water is analyzed by observing the change in color of the mixed fluid.
The non-pressurized ampule includes stem portions at opposite ends and is filled with a fluid, such as a medicine, at atmospheric pressure. To dispense the fluid, both stems are broken and the fluid is drained from the ampule.
There are no known ampules having positive displacement capabilities which permit the user to pump the fluid contained in the ampule therefrom. Further, there are no known positive displacement devices which store fluids with gases trapped in predictable volume regions.